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TREASURY DEPARTMENT 
UNITED STATES PUBLIC HEALTH SERVICE 

HUGH S. CUMMING, Surgeon General 

DIFFICULTIES IN COMPUTING CIVIL 
DEATH RATES FOR 1918 

WITH ESPECIAL REFERENCE 
TO EPIDEMIC INFLUENZA 



BY 

EDGAR SYDENSTRICKER 

Statistician 

AND 

MARY L. KING 

i 

Statistical Clerk 
United States Public Health Service 



REPRINT No. 583 

FROM THE 

PUBLIC HEALTH REPORTS 

Febbuaey 13, 1920 
(Pages 330-345) 




WASHINGTON 

GOVERNMENT PRINTING OFFICE 

1920 



vve^ 






*; »r b. 

NOV 19 1920 



^ 

^ 



DIFFICULTIES IN COMPUTING CIVIL DEATH RATES FOR 1918, 
WITH ESPECIAL REFERENCE TO EPIDEMIC INFLUENZA. 1 

By Edgar Sydensteickee, Statistician, and Maey L. King, Statistical Clerk, United States Public 

Health Service. 

Abnormal Conditions Affecting the Distribution of Population in 1918. 

Various conditions are known to have existed in 1918 which caused 
an abnormal distribution of population in the various demographic 
groups commonly employed in vital statistics. -Mention has been 
made already of them, such as (1) the withdrawal of over 4,000,000 
males of certain ages from civil life for the armed forces in the War 
with Germany, a condition which affected some localities more than 
others and which varied in its influence upon the sex and age com- 
position of the population at different times during the period begin- 
ning April, 1917; (2) the movement of population, particularly of 
persons of industrial ages, to localities and areas where war indus- 
tries were concentrated; (3) changes in the occupational status of the 
population, which were particularly important from the points of 
view of sex and age, since the number of women and the number of 
men above the usual wage-earning age were increased in some occu- 
pations; (4) a well-defined movement of negroes of certain ages from 
southern into northern and eastern States. 

It is obvious that, in expressing mortality rates and other ratios 
for the period in question, some account should be taken of these 
factors. Their effects are too important to be ignored or to be 
dismissed with the comforting guess that the more or less conflicting 
changes had "compensating" effects. Unfortunately, their maxi- 

i From the Statistical Office, United States Public Health Service. Acknowledgments are made to 
Dr. William H. Davis, chief statistician for vital statistics, Bureau of the Census, for the use of mortality 
data for Indiana and for computations of rates by certain methods to which specific reference is made in 
this paper. Reprint from the Public Health Reports, vol. 35, No. 7, Feb. 13, 1920, pp. 330-345. 

3 



4 COMPUTING CIVIL DEATH RATES FOR 1918. 

mum effect came in the latter part of 1918, when, because of the 
pandemic of influenza, especial interest was attached to the work of 
the vital statistician and the epidemiologist. 

A review of the literature so far published on 1918 vital statistics 
and on the statistics of the influenza epidemic will show that little 
account has been taken of the abnormal factors affecting the distri- 
bution of population, particularly from the points of view of sex and 
age. In a number of instances their possible effects upon mortality 
rates have been noted, but rarely has there been any attempt to 
express these effects statistically. Two very good reasons of a prac- 
tical nature can be given for this omission. One is the lack of reliable 
data upon which to base corrections of the usual intercensal estimates. 
Local estimates of additions to or subtractions from the number of 
persons of different sex, age, occupation, etc., in the population of a 
given community or section are so crude as to be almost worthless in 
the great majority of instances. 1 The other reason is that a decennial 
census will be taken as of January 1, 1920, and the natural disposition 
is to await the results of this enumeration before attempting to correct 
the preliminary computations based on estimated populations. Un- 
doubtedly the 1920 census will afford a more accurate basis for 1918 
rates than estimates based on the 1910 census, but it is important to 
note that the 1920 enumeration comes too late to give a true picture 
of the abnormal situation in 1918. Already many readjustments 
have taken place since 1918. Practically all of the males called to 
the colors in the War with Germany have returned to civil life. 
With the cessation of munitions making and with the reduction in 
the manufacture of products which were in unusual demand during 
the war, a movement of population away from many centers of "war 
industries" has set in. Even in those localities where the stimulus 
of war industries has continued there have doubtless occurred marked 
changes in the sex, age, and occupation distribution of persons em- 
ployed because of displacements that have followed the replacements 
occasioned by the war. So that even with the results of the 1920 
census before him, the vital statistician will be put to it to obtain 
reasonably accurate population bases for computing his ratios for 
1918. Certain modifications of population figures as enumerated for 
1920 will be necessary in estimating populations for 1918, and he will 
need all of the data that he can collect relating to purely local popu- 
lation changes and to males withdrawn from civil life. 

In view of the fact that it will be some time before the results of 
the 1920 census are known in any considerable detail, and in view of 
the practical necessity for as correct population bases as it is possible 
to get for use in computing preliminary rates, some consideration has 

1 At the same time more use can be made than has been made of statistics of employment, for example, 
for determining changes in population in communities. 



COMPUTING CIVIL, DEATH EATES FOR 1918. 5 

been given in this office to the question of making tentative cor- 
rections of population estimates, especially for sex and age, in com- 
puting influenza and pneumonia mortality rates for 1918. In the 
following pages an attempt is made to utilize such data as are avail- 
able relating to the withdrawal of males of certain ages from the civil 
population in 1918. In order to test the probable accuracy of rates 
computed upon the basis of population estimates corrected, or 
modified, from this point of view, a method of estimating population 
by the use of "normal" death rates from certain causes has been 
applied, and the results have been compared with the mortality curve 
for males according to age as computed from data collected among 
specially canvassed "sample" populations. 

Correction of Population Estimates by Taking into Account the Withdrawal of 
Males from Civil Life in 1918. 

The most complete information so far published relating to the 
number of males withdrawn from civil life during 1917 and 1918 is 
furnished in the Second Report of the Provost Marshal General. 1 
From these data several tables have been compiled in the belief that 
they may be of value to officers of health departments and others 
interested in vital statistics, and are presented herewith. 

Table I. — Number of males withdrawn from civil life in the United States from April 
1, 1917, to January 1, 1919, by months, and the percentages they were of total pop- 
ulation, of males of all ages, and of males of ages 18-4-5, inclusive. 



Months (1917-18). 



Males withdrawn from civil life — Ages 18-45. 



Number. 



By months. 



Cumulative. 



Cumulative per cent of— 



Total 
popula- 
tion. 



Males. 



All ages. 



Ages 
18-45. 



Total 

1917— April 

May 

June 

July 

August 

September 
October. . . 
November. 
December . 
1918— January . . . 
February. . 

March 

April 

May 

June 

July 

August 

September 
October... 
November. 



4,178,172 



4, 178, 172 



100. 00 



100.00 



113, 633 
146, 868 
150,249 

85,838 

66, 172 
324,248 
210,392 

90,395 
194, 700 

93,522 
121,693 
169, 791 
220,079 
428,466 
431,582 
452, 417 
346,924 
273,080 
249, 185 
8,938 



113, 633 

260, 501 

410, 750 

496, 588 

562, 760 

887,008 

1,097,400 

1,187,795 

1,382,495 

1,476,017 

1,597,710 

1,767,501 

1,987,580 

2,416,046 

2,847,628 

3,300,045 

3,646,969 

3,920,049 

4, 169, 234 

4,178,172 



.11 

.25 

.40 

.48 

.54 

.85 

1.05 

1.14 

1.32 

1.41 

1.53 

1.69 

1.89 

2.30 

2.71 

3.13 

3.46 

3.71 

3.94 

3.94 



.21 
.49 

.77 
.93 
1.05 
1.66 
2.05 
2.22 
2.58 
2.75 
2.97 
3.28 
3.68 
4.47 
5.26 
6.10 
6.72 
7.22 
7.67 
7.67 



100.00 



.48 
1.10 
1.73 

2.09 
2.36 
3.72 
4.60 
4.97 
5.78 
6.16 
6.66 
7.36 
8.26 
10.03 
11.80 
13.66 
15.08 
16.18 
17.19 
17.21 



1 Crowder, E. H., Second Report of the Provost Marshal General on the Operations of the Selective 
Service System to Dec. 20, 1918, Government Printing Office, Washington, D. C.,1919. This report covers 
the period from May 18, 1917, the date of the selective service act, to Dec. 20, 1918, and contains also in- 
formation relating to voluntarv enlistment 5 'F the Army, Navy, and Marine Corps for the same period. 



6 COMPUTING CIVIL DEATH EATES FOR 1918. 

Table I-A. — Estimated number of persons of specified sex and ages in total population 

of the United States. 



Age and sex. 


July 1, 1917. 


July 1, 1918. 


All ages: 


103,635,306 

53,268,547 
23,757,772 


105,253,300 


All ages: 


54, 100, 19(i 


Males: 


24,128,687 







In Table I are shown the monthly increments and total increase of 
the armed forces of the United States (inductions through the selec- 
tive service, and enlistments in the Army, Navy, and Marines) during 
the period April, 1917, to November, 1918, exclusive of the inductions 
in October and November, 1918, which were on account of the third 
registration. The last inductions mentioned were nearly all of stu- 
dents in schools and colleges, made just before the armistice was 
signed, and, for practical purposes, the men so inducted need not be 
considered as withdrawn from civil life. Taking the male population 
of the age group 18 to 45, inclusive, in the United States, estimated 
as of July 1, 1917, and July 1, 1918, as the bases, the cumulative per 
cent withdrawn from civil life at the end of each month from April 1, 
1917, to November 30, 1918, has been computed. In Figure I the 
monthly increments as well as the cumulative totals and the percent- 
ages referred to have been plotted. It will be noted that at the 
time of the influenza epidemic in October and November, 1918, the 
civil population had been decreased by something over 4,000,000 
persons. This was equivalent to nearly 4 per cent of the entire pop- 
ulation, nearly 8 per cent of the entire male population, and about 17 
per cent of males in the ages 18 to 45, as estimated for July 1, 1918. 
While the figures are not absolutely accurate, particularly in that no 
account can be taken of the discharge of soldiers from camps or of 
commissioned officers, 1 they are sufficiently correct to show that the 
number of males of these ages in civil life was so considerably de- 
creased that any computation of specific mortality rates, for example, 
according to age, based on the estimated population without allowing 
for withdrawals on account of military duty, would be seriously 
erroneous. 

Since neither the total population nor the number of males of all 
ages nor the number of males of specific ages in continental United 
States is ordinarily used in computing mortality rates, Table I does not 
afford any data for practical use except the cumulative percentages by 
months. Similar data for States or smaller divisions are not afforded, 

1 It appears that 8. 1 per cent of men actually inducted into service during the period Feb. 10-Nov. 1, 1918, 
were later rejected on physical examinations after reaching camp (Second Report of the Provost Marshal 
General, p. 420, Table 56-A). How large a percentage of enlisted men was rejected for this reason is not 
stated, so far as the writers are able to ascertain. The figures given in Table I are therefore somewhat high. 
On the other hand, about 230,000 commissioned officers are not included in Table I. 



COMPUTING CIVIL DEATH RATES FOR 1918. 



but the monthly cumulative percentages for the country as a whole 
can be applied to the State totals (as given in Table II) or to totals 
for localities that can be determined from State enlistment figures 
and from the returns from local exemption boards which are published 
in the report referred to. Upon the assumption that the population 



NUMBER OF MEN WITHDRAWN FROM CIVIL LIFE AND PER CENT THEY WERE OF 
MALES OF THE AGES 18-45 IN THE TOTAL POPULATION BY MONTHS, 1917-1918 




AMJJASOND 
1917 



JFMAMJJASON 
1918 



Figure 1. 



in each locality or larger division was affected in about the same way 
as the population of the country at large, a rough approximation 
can be made of the number of withdrawals of males from civil life 
at the end of any month in the locality or section in question. This 
approximation, of course, can be used in connection with the percent- 
age distribution of males actually withdrawn (see Tables III and IV) 



g COMPUTING CIVIL DEATH RATES FOE 1918. 

and some crude estimate can he made of the population in different 
age groups remaining in civil life at the end of any month in the period 
from April 1, 1917, to November 30, 1918. 

In Table II are given the total increments to November, 1918, 
from various sources in each State. The figures for white and colored 
combined are available for men inducted but not for men enlisted. 
Since only 1.5 per cent of enlisted men were colored, however, the 
number of colored males for practical purposes is negligible. 

Table II.— Enlistments and inductions, Apr. 2, 1917, to Oct. 81, 1918, under first and 
second registrations, compared by States. 1 





Total 
incre- 
ment. 


Total 

in- 
ducted. 


Total 
en- 
listed. 


White. 




Locality. 


Total. 


In- 
ducted. 


Enlisted. 


Colored 

in- 
ducted. 




Army. 


Navy. 


Marines. 




United States 


4,034,743 


2,666,867 


1,367,876 


3,667,033 


2,299,157 


877,458 


437,527 


52, 891 


367, 710 




73, 543 

11,410 

65,311 

131,484 

38, 751 

55, 218 

7,985 

17,945 

36,211 

86,973 

20, 467 

272, 235 

104,973 

101,638 

66,645 

77,983 

71, 271 

26, 602 

51, 700 

157,101 

142,397 

106, 918 

56, 740 

140, 257 

39, 049 

49,614 

5,488 

14,970 

118,350 

13,586 

410,569 

74, 705 

27, 253 

205, 852 

84,909 

34,430 

313,297 

22, 270 

54,284 

30, 130 

80, 139 

174,061 

19,421 

11,223 

78,524 

55, 433 

55, 895 

101,696 

12, 223 

2, 105 

5, 733 

16,490 

1,286 


59, 755 

8, 113 

49,312 

67,067 

22,858 

32, 539 

4,993 

9,631 

24,916 

66,841 

12,566 

177,483 

69, 749 

66,864 

41,905 

58,330 

56,205 

15, 266 

33, 867 

76, 567 

96, 480 

73,680 

43,362 

92,843 

27,340 

29, 807 

3,164 

8,404 

71,390 

8,862 

253,589 

58, 441 

18, 595 

138, 148 

64,941 

16, 158 

201, 211 

11,176 

44, 059 

21,255 

59, 878 

117,395 

10, 788 

6,629 

58,337 

28, 686 

45, 355 

70,982 

7,923 

1,962 

5,466 

15, 734 


13, 788 

3,297 

15, 999 

64,417 

15, 893 

22,679 

2,992 

8,314 

11, 295 

20, 132 

7,901 

94, 752 

35, 224 

34, 774 

24, 740 

19, 653 

15,066 

11,336 

17,833 

80, 534 

45,917 

33,238 

13,378 

47,414 

11, 709 

19, 807 

2,324 

6,566 

46,960 

4,724 

156, 980 

16,264 

8,658 

67, 704 

19,968 

18, 272 

112,086 

11,094 

10,225 

8,875 

20, 261 

56, 666 

8,633 

4, 594 

20, 187 

26, 747 

10, 540 

30, 714 

4,300 

143 

267 

756 

1,286 


47,669 

11,333 

47, 767 

130, 565 

38, 380 

54, 277 

6,620 

13,945 

23,307 

52,670 

20,372 

263, 481 

100,394 

100, 709 

64,518 

66, 663 

42,560 

26, 552 

42,488 

155, 901 

140, 002 

106,407 

32, 674 

131,038 

38,851 

48,972 

5,462 

14, 943 

113,487 

13,535 

404,376 

54,623 

27, 166 

197,991 

79, 215 

34,362 

297, 905 

21,979 

28, 486 

30, 068 

62,365 

142, 555 

19,344 

11, 201 

54,983 

55, 260 

50, 403 

101, 472 

12, 128 

2,100 

5, 733 

16, 490 

1,286 


33,881 

8,036 

31, 768 

66, 148 

22,487 

31,598 

3,628 

5,631 

12,012 

32,538- 

12,471 

168, 729 

65, 170 

65,935 

39, 778 

47,010 

27, 494 

15, 216 

24, 655 

75,367 

94, 085 

73, 169 

19,296 

83,624 

27, 142 

29,165 

3,138 

8,377 

66, 527 

8,811 

247,396 

38,359 

18, 508 

130, 287 

59, 247 

16,090 

185,819 

10, 885 

18, 261 

21,193 

42, 104 

85,889 

10, 711 

6,607 

34, 796 

28, 513 

39,863 

70, 758 

7,828 

1,957 

5,466 

15, 734 


9,562 

1,S54 

11,699 

38, 992 

9,670 

13,151 

2,003 

4,442 

6,834 

14, 160 

4,955 

61,938 

25, 847 

26,389 

18,217 

13,934 

7, 570 

7,290 

10,144 

41,985 

32, 403 

20, 272 

9,044 

29,863 

7,331 

14,416 

1,888 

4,408 

28,333 

3,649 

89,031 

10, 573 

6,611 

48,885 

14, 105 

10, 626 

78, 671 

5,436 

6,505 

7,083 

13, 563 

37, 704 

5,335 

3,088 

10, 556 

12, 761 

7,359 

22,349 

3, 554 

143 

267 

756 

254 


3, 938 
1,269 
4,025 

23,058 
5,075 
9,319 
919 
3,500 
4,375 
5,382 
2,450 

28,264 
8,313 
7,832 
5,907 
5,163 
6,782 
4,025 
6,913 

36, 884 

11,463 

10, 588 
4,069 

14,132 

3,281 

4,944 

350 

2,100 

17,457 
1,050 

61, 779 
5,250 
1,838 

14, 176 
5,513 
6.694 

29,446 

5,600 

3,675 

1,663 

5,425 

16,889 

2,494 

1,488 

9,144 

12,382 

2,625 

7,569 

656 


288 

174 

275 

2,367 

1,148 

209 

70 

372 

86 

590 

496 

4,550 

1,064 

553 

616 

556 

714 

21 

776 

1,665 

2,051 

2,378 

265 

3,419 

1,097 

447 

86 

58 

1,170 

. 25 

6,170 

441 

209 

4,643 

350 

952 

3,969 

58 

45 

129 

1,273 

2,073 

804 

18 

487 

1,604 

556 

796 

90 


25,874 




77 




17, 544 




919 




371 




941 




1,365 


District of Columbia 


4,000 
12,904 




34,303 




95 




8,754 




4,579 




929 




2,127 




11,320 




28, 711 




50 




9,212 




1,200 




2,395 




511 




24,066 




9,219 




198 




642 




26 


New Hampshire 


27 

4,863 




51 




6,193 




20,082 




87 


Ohio 


7,861 




5,694 




68 




15,392 




291 




25, 798 




62 




17, 774 




31, 506 


Utah 


77 




22 




23,541 




173 




5,492 




224 




95 




5 




















394 


638 













1 Compiled from the second report of the Provost Marshal General, pp. 468 and 459. 



COMPUTING CIVIL DEATH KATES FOE 1918. 9 

The report of the Provost Marshal General already referred to 
shows for each local exemption board the number of men accepted 
at camp, but it does not give the number of enlisted men from each 
locality. Here again rough approximation must be resorted to. 
The number of men withdrawn from a given locality by enlistments 
can be estimated by using the ratio of inductions to enlistments for 
the particular State and applying it to the inductions from the 
locality. This, however, will afford rather doubtful results except 
possibly for the large population centers. 

Since the males withdrawn from the civil population were almost 
entirely within the ages 18 to 45, and principally within the ages 
21 to 31, corrections of population estimates for males of specific ages 
or age groups are especially important. Unfortunately, no tabula- 
tion by years of age of the number of men inducted into or enlisted 
in the armed forces has as yet been published. 1 About the closest 
approximations that can be made are from the percentage distribu- 
tion of registered men actually placed in Class I for the country as a 
whole, 2 and from Army and Navy estimates (based on sampling) 
of the number of enlisted men who were of the ages under 21 and 
over 30. 3 Since no statistics are available as to the distribution of 
enlisted men in the age group 21 to 30, we must assume that the dis- 
tribution was the same as for the selective service men who were 
actually placed in Class I. Without presenting the detailed compu- 
tations, the approximations arrived at are presented in Table III, 
which shows the number of men of each age and the percentage 
they were of totals inducted and enlisted in the various services in 
the United States as a whole. For reasons that are apparent, the 
figures thus obtained are approximations only, but it is believed that 
they afford reasonably accurate percentages of distribution which 
can be utilized in making estimates for States or smaller geographic 
divisions. Since 5-year age groups ordinarily are utilized in com- 
puting rates, the percentage distribution given in Table III is sum- 
marized by 5-year age groups in Table IV. 

i The Provost Marshal General's second report gives in detail the number of men by years of age who 
were registered for selective service in each State, but not the number of men by years of age who were aetu. 
ally inducted or who had enlisted. A tabulation is presented showing, for men inducted in 1917, the propor- 
tions of registered males for each year of age from 21 to 30, inclusive, who were placed in Class I for the country 
as a whole (Id. p. 189, Table 67). The percentageo varied from 46.3 for those 21 years of age to 22.1 for those 
30 years of age. If it can bo assumed that these ratios held for any State (and probably they are suffi- 
ciently accurate for the purpose), the number of men placed in Class I can be estimated for each year of age. 
It is not believed, however, that this method would yield more accurate estimates than the one which is 
immediately suggested. 

2 Id, p. 189, Table 67. 

3 Id. p. 317. 

187584°— 20 2 



10 



COMPUTING CIVIL DEATH RATES FOR 1918. 



Table III. — Number of males withdrawn from civil life for service in the armed forces, 
and estimated number in each age, during 1917 and 1918, in the United States. 









Enlistments. 






Age. 


Total. 


Army. 


Navy. 


Marines. 


Total 
enlistments. 


Inductions. 




Num- 
ber. 


Per 
cent. 


Num- 
ber. 


Per 
cent. 


Num- 
ber. 


Per 
cent. 


Num- 
ber. 


Per 
cent. 


Number. 


Per 

cent. 


Num- 
ber. 


Per 
cent. 


All ages. 


4,034,743 
62,210 
352, 526 
819, 577 
403,718 
374,888 
335,807 
294,061 
2G8, 646 
2)7,398 
213,981 
209,067 
219,317 
203, 547 


100.0 
1.5 
S.8 
20.3 
10.0 
9.3 
8.3 
7.3 
6.7 
6.1 
6.1 
5.2 
5.4 
5.0 


877,458 
35,537 

201,377 
73, 522 
66, 520 
61,519 
55,017 
48,515 
44,013 
40,512 
40,012 
34,510 
36,011 

140,393 


100.0 
4.0 

23.0 
8.4 
7.6 
7.0 
6.3 
5.5 
5.0 
4.6 
4.6 
3.9 
4.1 

16.0 


437,527 
24,611 

139,461 
32,158 
29,096 
26,908 
24,064 
21,220 
19,251 
17,720 
17, 501 
15,095 
15,751 
54,691 


100.0 
5.6 
31.9 
7.4 
6.6 
6.2 
5.5 
4.8 
4.4 
4.0 
4.0 
3.4 
3.7 
12.5 


52,891 
2,062 

11,688 
4,510 
4,080 
3,773 
3,374 
2,976 
2,700 
2,485 
2,454 
2,117 
2,209 
8,463 


100.0 
3.9 

22.1 
8.5 
7.7 
7.2 
6.4 
5.6 
5.1 
4.7 
4.6 
4.0 
4.2 
16.0 


1,307,876 
62,210 
352, 520 
110,190 
99, 096 
92,200 
82, 455 
72,711 
65,964 
00,717 
59,967 
51,722 
53,971 

1,203,547 


100.0 
4.6 
25.8 
8.1 
7.3 
6.7 
6.0 
5.3 
4.8 
4.4 
4.4 
3.8 
3.9 
14.9 


2,666,867 


100.0 


19-20 

21 


C 1 ) 

709,387 
304,022 
282, 688 
253, 352 
221,350 
202, 6S2 
186, 681 
184,014 
157,345 
105,316 


26.6 


22 


11.4 


23 


10.6 


24 


9.5 


25 


8.3 


26... 


7.6 


27 


7.0 


28 


6.9 


29 


5.9 


30 


6.2 


" r3 ° 











1 143,429 were inducted from the third registration, presumably college students enrolled in student 
Army camps. They are not included here. 

Table IV. — Approximated percentages of males enlisted in the Army, Navy, and Marines, 
ana inducted during 1917-18, who were in specified age groups. 



Age groups. 


Enlisted. 


Inducted. 


Army. 


Navy. 


Marines. 


Total. 




100.0 
15.5 
40.8 
27.7 
10.0 


100.0 
21.6 
41.6 
24.3 
12.5 


100.0 
15.0 
40.8 

28.2 
16.0 


100.0 
17.5 
41.0 
26.6 
14.9 


100 


15-19 




20-24 


58.1 


25-29 


35.7 




6.2 







With these data before us, the following method of utilizing them 
in correcting population estimates for the latter part of 1918, from 
the single point of view of withdrawals of males from civil life, seems 
to be logical and practicable: 

For a given State, find the number of males inducted (Table II) 
and multiply this number by the percentages for different ages for 
inducted men (Table III or Table IV). The resulting figures are 
the estimated number of males of different ages or age groups with- 
drawn from civil life by the selective service law. Proceed in the 
same manner for men enlisted in each of the different services (Army, 
Navy, and Marines) . Summate for each age or age group the num- 
ber of men withdrawn by inductions and enlistments, and subtract 
from the estimated male population as of July 1, 1918, in correspond- 
ing ages or age groups. The remainder will be an estimate of the 
male population of the ages specified who were in civil life at the 
time under consideration. 



COMPUTING CIVIL DEATH RATES FOR" 1918. H 

Population Estimates on the Basis of Normal Death Rate from Selected Causes. 

For localities or sections where no other causes are known to have 
affected distribution of population according to age, occupation, etc., 
in an appreciable degree, a correction of the effect of withdrawals 
of males for military service will be sufficient. The vital statistician 
must, of course, determine from such information as he can obtain 
whether or not any other important causes were at work. 

It is safe to say, however, that in a number of States and localities 
abnormal conditions other than the withdrawal of males for mili- 
tary service did affect the population. In any event, it is highly 
desirable to have some criterion by which the combined influences 
■of the various possible conditions may be expressed statistically. 
Sampling by means of actual enumerations was not resorted to, except 
in a few instances for special purposes. Is there any other method 
simple enough for every day use? We are indebted to the division 
of vital statistics of the Bureau of the Census for a method which 
lias been used in checking estimates arrived at by conventional 
procedure. 

A death rate is made up of two factors: The number of persons 
in the group considered and the number of deaths occurring among 
those persons from the cause or causes in question. The usual 
formula is 

Number of deaths X 1,000 



Population 



Kate 



If the death rate during a normal period from certain causes be 
used as the divisor and the number of deaths (multiplied by 1,000) 
from the same causes during the period for which a population 
estimate is desired be the dividend, the quotient will be the desired 
estimate of the population. To illustrate: 

Let the number of deaths from all causes, other than acute infections 
diseases, among males of the age group 20 to 24 during the period 
September-December, 1918, = 300. Let the death rate from the same 
causes among males # of the same ages during a period which is as- 
sumed to be normal; e. g., the average for September-December for 
the years 1909-1911 = 2 per 1,000. Then 

300 X 1,0 00 _ 160[000 

which is an estimate of the number of males in September-December, 
1918. Of course this estimate involves several assumptions, impor- 
tant among which is that the death rate of 2 per 1,000 from the 
causes specified did not change from 1909-1911 to 1918. But grant- 



12 



COMPUTING CIVIL DEATH EATES FOR 1918. 



ing that this estimate is fairly accurate, the specific rate for any 
disease for 1918 may be computed. 1 

A Comparison of Rates Derived from Different Population Estimates made by 
the Various Methods Described. 

It will be of interest now to compare the results derived by the use 
of the various methods described. 

The deaths from influenza and pneumonia (all forms) during the 
four months' period, September 1 to December 31, 1918, among 
males of different ages in Indiana are used (Table V). Three sets of 
annual rates are computed; namely, (1) a rate based on the number 
of males in each age group as estimated for July 1, 1918, by the 
usual arithmetic method" for intercensal years; (2) a rate based on 
the number of males in each age group as estimated in (1), but after 
subtracting, for certain age groups, the number of males withdrawn 
from civil life up to November 30, 1918; (3) a rate based on the 
normal death rate from all causes except pneumonia (all forms), 
computed according to. either of the two methods used by the vital 
statistics division of the Bureau of the Census. For convenienc3 we 
may denote them as rate 1, rate 2, and rate 3. 

Table V. — Number of deaths from influenza and pneumonia (all forms) and from all 
other causes among males in Indiana Sept. 1,-Dec. 31, 1918. 



Age groups. 


Influenza 
and pneu- 
monia (all 
forms). 


All other 
causes. 




833 

187 

166 

360 

371 

611 

619 

452 

214 

117 

87 

61 

66 

209 


1,042 




107 




103 




161 




143 




188 




199 




227 




224 


45 to 49 


262 


50 to 54 


261 




286 


60 to 64 


423 




1,880 







i This method involves a good deal of arithmetical labor, and practically the same result is obtained by 
a shorter procedure employed by the vital statistics division of the Bureau of the Census. This procedure 
involves exactlv the same principle as the one described above, but the actual computation of a new esti- 
mate of population is eliminated. For example, in checking the accuracy of the calculated death rates 
from influenza and pneumonia in Indiana during September-December, 1918, rough death rates were 
found as follows: Graduated data of 1909, 1910, and 1911 were first used to find a set of normal death rates 
by age and sex as in the construction of a life table. To make these rates more nearly accord with rates 
based on all deaths except influenza and pneumonia (all forms) to total deaths, the percentages of deaths 
from pneumonia (all forms) to total deaths by ages and sex in 1910 were calculated and the life-table rates 
reduced to corresponding amounts. (No allowance was made for influenza deaths in 1910 as this was 
considered an unnecessary refinement for this rough calculation.) The resulting death rates were assumed 
to represent the death rates from all causes except influenza and pneumonia (all forms) as primary causes 
in the last four months of 1918, and rough death rates were then calculated in the following manner: The 
per cent of total deaths in the last four months of 1918 which were from influenza and pneumonia (all forms) 
was divided by the per cent which were from all other causes. The quotient was then multiplied by the 
assumed normal annual death rate from all causes except pneumonia (all forms) based on graduated data 
of 1909, 1910, and 1911. The product is a rough annual death rate from influenza and pneumonia (all forms) 
for the last four months of 1918 among persons of a specific sex and age. 



COMPUTING CIVIL DEATH RATES FOE 1918. 



13 



In computing rates 1 and 2, the detailed population estimates are 
presented for purposes of illustration in Table VI. The number of 
males in each age group as estimated by the usual arithmetic method 
for intercensal years is shown in the first column. In the next five 
columns are shown the number of males withdrawn from civil life, 
approximated according to the procedure previously outlined. In 
the last column is given the estimated number of males in each age 
group after allowing for these withdrawals. 

Table VI. — Number of males of different ages in Indiana, estimated as of July 1, 1918, 
by arithmetic method and after deducting therefrom males withdrawn from civil life in 
1917 and 1918. 





Male popu- 
lation, 
estimated 
as of July 
1, 1918. 


Number of males withdrawn from civil life. 


Male-popu- 
lation 


Age groups. 


Total. 


In- 
ducted. 


Enlisted. 


estimates, 
less males 
withdrawn 




Army. 


Navy. 


Marines. 


from civil 
life. 




1,459,3.53 

148,043 
142,066 
136, 535 
138, 586 

133,999 
123, 154 
106,605 
103,154 

90,604 
77,681 
75,345 
55,955 

45,797 
81,829 


104,973 


69,749 


25,847 


8,313 


1,064 


1,354,380 


Under 5 


148, 043 


5to9 












142, 066 


10 to 14 












136, 535 
132, 623 


15 to 19 


5,963 

54,961 
34,380 
9,669 




4,007 

10,545 
7,160 
4,135 


1,796 

3,458 
2,020 
1,039 


160 

434 
300 
170 


20 to 24 


40,524 
24,900 
4,325 


79,038 


25 to 29 


89, 774 


30 to 34 


96, 936 


35 to 39 


103, 154 
90,604 


40 to 44 












45 to 49 












77, 681 


50 to 54 












75,345 
55,955 


55 to 59 












60 to 64 












45,797 














81,829 

















In Table VII are shown the annual rates computed by the three 
methods. These rates are plotted in Figure 2. 

Table VII. — Annual death rate per 1,000 males of different ages in Indiana from 
influenza and pneumonia (all forms), September-December, 1918, computed upon the 
bases of various estimates of population. ' 



Age groups. 


1 

Based on popu- 
lation as esti- 
mated by 
arithmetic 
method. 


2 

Same as 1, but 
after allowing 
for withdrawal 
of males from 
civil life. 


3 

Based upon 
normal death 
rate from all 
causes other 

than 
pneumonia. 


Under 5 


16.8 
3.9 
3.6 
7.8 

8.3 
14.8 
17.3 
13.1 

7.1 
4.5 
3.5 
3.3 

4.3 
7.6 


16.8 
3.9 
3.6 
8.1 

14.0 
20.4 
20.1 
13.1 

7.1 
4.5 
3.5 
3.3 

4.3 
7.6 


20.4 


5 to 9 


4.7 


10tol4 


3.7 


15 to 19 


8.2 


20 to 24 


13.8 


25 to 29 


16.8 


30 to 34 


18.4 


35to39 


12.8 


40 to 44 


7.2 


45 to 49 


4.3 


50 to 54 


3.8 


55 to 59 ...<-. 


3.8 


60 to 64 


4.0 


65 and over 


8.6 







14 



COMPUTING CIVIL DEATH KATES FOR 1918. 



It will be observed that the rates are practically identical for all 
ages except those between 15 and 35, thus indicating the fact that 
certain conditions existed which disturbed the normal age distribu- 
tion of the male population of those ages. Which of the three rates 



DEATH RATES FROM INFLUENZA AND PNEUMONIA AMONG MALES 
SEPTEMBER-DECEMBER 1918 IN INDIANA: VARIOUS ESTIMATES OF POPULATION 



Death Rates Computtd 

1 . l^pon the basis of males estimated 

as of Julu, 1.H18 

2 . Same as 1 , but allowing for withdrawal 
of males from civil life in W17-1918 -- 

3 . Mpon the basis of males as estimated 
from deaths from "normaJ * or "constejst , 
causes _ 




10 15 20 25 30 35 40 45 50 55 60 65 

AGE IN YEARS 



Figure 2. 



is the correct one ? Or, rather, which of the three rates most nearly 
approximates the correct rate ? Rate 1 is much lower, particularly 
in the age group 20 to 24, than rates 2 and 3, suggesting the conclusion 
that the computation of a mortality rate upon the basis of an estimated 



COMPUTING CIVIL DEATH EATES FOR 1918. 



15 



population without taking into account the withdrawal of males from 
civil lif e is quite inaccurate. As between rates 2 and 3 , the suggestion 
is offered that rate 2 is too high because the withdrawal of males from 
civil life may have been compensated by an abnormal addition of 





C0MPARIS0N OF THE RELATIVE VARIATIONS IN DEATH RATES FROM • 




INFLUENZA AND PNEUMONIA AMONG MALES OF DIFFERENT AGES 






BASE : ARITHMETIC AVERAGE OF THE 5PECIFIC RATES 


INDICES 


















300" 
250- 
















1. Indiana.: Upon the basis of males estimat 
as of July 1.W18 

2 Indiana: Same as 1 , but allowing for w 
of males from civil life in 1117-1<)18 

3 Indiana: Upon the basis of males as est 
from deaths from *normal*or 'constant 
causes 


ed 


ithdrawal 
mated 














lr\ 


"■-» 


enumerated populations 

Cinfluenza. surveys of U.S.P.H.S.) — .• — —- 


200- 


1 








t 


1! 

} 


\ \ 
















T 








a 

*> 




A 
















mo. 


I 








I 


A 


\ 


\\\ 
















1 








i y 






\v 














100- 
SO 


l 






i 


[/ 






w 


\ 

v\\ 














I 


; 


I 










\V 


^0— . 


"A 




J 


o 

t 




















\^> 






£j 




0- 


5 1 


15 20 25 30 35 40 45 50 55 50 65 
AGE IN YEARS 



Figure 3. 



males in certain occupations. In weighing the relative accuracy of 
rates 2 and 3, however, we must take into consideration other possible 
conditions, as, for example, the demand in Indiana for males of these 
ages for employment in the so-called war industries. As a matter of 



16 



COMPUTING CIVIL DEATH RATES FOR 1918. 



fact, Indiana was a State where comparatively few war industries were 
located and there was a tendency toward emigration rather than 
toward an immigration. 

In order to test this assumption the various curves already com- 
puted may be compared with the mortality curve among males of a 
canvassed population. Accordingly, in Figure 3 the rates have been 
reduced to a relative basis, and a fourth curve — that of mortality 
from influenza and pneumonia among males of different ages who 
were actually canvassed in the course of special influenza surveys 
made in various localities in the United States by the Public Health 
Service — has been fitted in. This fourth curve, which we may de- 
note as rate 4, is considered as the normal. 

If it be true that rate 4 can properly be regarded as a normal one 
for the period of the influenza epidemic, it is clearly indicated that 
(Table VIII and Fig. 3) the rate which most closely approximates it 
for Indiana is rate 2. 1 



Table VIII. — Comparison of the relative variations in death rates from influenza and 
pneumonia (all forms), computed by various methods for males of different ages in 
Indiana, September-December, 1918, with that in areas where special surveys were made. 

[Base: Arithmetic average of the specific rates.] 



Age groups. 


1 

Population 
estimated 
by usual 
method. 


2 

Same as 1, 
but after 
allowing for 
males with- 
drawn from 
civil life. 


3 

By census 
method. 


4 

Localities 
canvassed. 


Under 5 


202 
47 
43 
94 

100 
178 
208 

158 

86 
54 

42 
40 

52 
92 


202 

47 
43 
98 

169 
246 
242 

158 

86 
54 
42 
40 

52 
92 


219 
51 
40 

88 

148 
181 
198 
138 

77 
46 
41 
41 

43 
92 


149 


5 to 9 


37 


10 to 14 


27 


15 to 19 


78 


20 to 24 


133 


25 to 29 


261 


30 to 34 


178 


35 to 39. 


155 


40 to 44 


80 


45 to 49 


69 


50 to 54 


65 


55 to 59 


37 


60 to 64 


43 




82 







A similar result has been found in comparing rates computed upon 
the various bases for other sections and localities. 

In this connection it may be noted that if the ratio be computed 
for each age group of the number of males and of females enumerated 
in the special influenza survey made in Baltimore, Md., during 
December, 1918, to that enumerated in the 1910 census of the same 

i The divergences of the rates in the ages 40 and over are probably due to a paucity of data, since the 
number of deaths and the number of persons in those ages in the special surveys were rather small. 



COMPUTING CIVIL DEATH RATES FOR 1918. 



17 



city, it will be seen that a very marked depletion of males of the ages 
18 to 35 occurred. This has been done in Table IX and plotted in 
Figure 4. While the number of persons included in the survey was 
relatively small (about 32,000), and the sample is not large enough 
to afford as great regularity in results as would be desirable, the 



RATIO OF NUMBER OF PERSONS OF DIFFERENT AGES ENUMERATED IN SAMPLE 
AREAS IN BALTIMORE IN 1918 TO THAT ENUMERATED IN THE ENTIRE CITY IN 1910 




10 15 20 25 30 35 40 45 50 55 60 65 70 75 

AGE IN YEARS 



great divergence of the distribution of males in the ages 18 to 34 
from that of males and females in the same ages in 1910 in Decem- 
ber, 1918, is unmistakably manifest. Here, therefore, in a center 
of industrial activity the depletion of the male population of military 
age far outweighed accretions. 



18 



COMPUTING CIVIL DEATH RATES FOR 1918. 



Table IX. — Ratio of number of persons of different ages enumerated in sample areas 
in Baltimore in 1918 to that enumerated in the entire city in 1910. 





Population. 


Ratio, 1918 to 1910. 


Indices of ratios. 


Age period. 


Beth sexes. 


Male. 


Female. 


Both 

sexes. 


Male. 


Fe- 
male. 


Both 
sexes. 


Males. 


Fe- 




1910 


1918 


1910 


1918 


1910 


1918 


males. 




557, 790 


31,697 


267, 897 


14,677 289,893 


17, 020 


0. 0568 


0.0548 


0. 0587 


100 












Under 5 

5 to 9 

10 to 14 
15 to 19 

20 to 24 
25 to 29 

30 to 34 

35 to 39 . 

40to44 

45to49 

50to54 

55 to 59 

60 to 64 

65 to 69 
70t->74 
75 and over. 


51,986 
49,617 
48, 507 
54,253 

58,713 
54,311 
45, 604 
43, 163 

36,963 
31,627 
26,510 
18, 607 

14,351 
10,454 
6,647 
6,477 


3,226 
2,988 
2,826 
2,815 

2,749 

2,826 
2,758 
2,445 

2,057 
1,880 
1,631 
1,071 

936 
663 
417 
409 


26, 189 
24, 739 
23, 564 
25, 124 

27, 373 
26, 127 
22, 195 
21, 029 

17, 852 
15,367 
12, 856 
8,987 

6,541 

4, 662 
2,800 
2,492 


1,641 
1,500 
1,375 
1,304 

959 
1,138 
1,260 
1,207 

1,000 
912 
784 
499 

452 
311 
170 
165 


25, 797 
24, 878 
24,943 
29, 129 

31,340 
28,184 
23,409 
22, 134 

19,111 
16,260 
13, 654 
9,620 

7,810 
5,792 
3,847 
3,985 


1,585 
1,488 
1,451 
1,511 

1,790 
1,688 
1,498 
1,238 

1,057 

968 
847 
572 

484 
352 
247 
244 


.0621 
.0602 
. 0583 
.0519 

.0468 
.0520 
.0605 
.0566 

.0557 
. 0594 
.0615 
.0576 

.0652 
.0634 
. 0627 
. 0631 


.0627 
.0606 
. 0584 
.0519 

. 0350 
.0436 
.0568 
. 0574 

.0560 
.0593 
.0610 
.0555 

.0691 

.0667 
.0607 
.0662 


.0614 
.0598 
.0582 
.0519 

.0571 
.0599 
.0640 
.0559 

.0553 
.0595 
.0620 
.0595 

.0620 
.0608 
.0642 
.0612 


109 
106 
103 
91 

82 

92 

107 

100 

98 
105 
108 

101 

115 
112 
110 
111 


Ill 
107 
103 
91 

62 
77 
100 
101 

99 
104 
107 

98 

122 
117 
107 
117 


108 
105 
102 
91 

101 
105 
113 
98 

97 
105 
109 
105 

109 
107 
113 
108 



Unless in a given locality there are known to have been considerable 
accretions to the male population of the ages under consideration, 
which offset the depletion due to withdrawals for military service, 
rates based on the estimated number of total males or females in each 
age group, after allowing for withdrawals for military service, will be 
more accurate than rates which do not take into account these with- 
drawals. Probably they will be more nearly correct than rates com- 
puted on the basis of " normal" death rates. 

At best, such corrections as can be made of population estimates 
for 1918 are very rough approximations. The foregoing may prove 
suggestive to health departments as rather simple methods for making 
corrections for the withdrawal of males of certain ages from civil life, 
and for testing rates based upon "corrected" and "uncorrected" 
population estimates. 



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